Anti-theft device for a vehicle

ABSTRACT

In a vehicle control device having a so-called keyless entry system in which a door lock control unit controls a door lock actuator by receiving a signal representing an identification code and transmitted from a transmitter, an internal-combustion engine control unit computes fuel injection quantity and ignition timing from control data stored in a memory in response to detection results inputted from respective detectors, and thereby drives a fuel injection valve and an igniter. The door lock control unit detects whether a theft is attempted on the vehicle, based on the switching states of various switches, and supplies the result of the detection to a constant-voltage circuit in the internal-combustion engine control unit in the form of a code signal; when a theft is detected, power supply to respective circuits in the internal-combustion engine control unit is shut off. Furthermore, the internal-combustion engine control unit checks whether the identification code received by a receiver matches the identification code prestored in the memory, and if they do not coincide, inhibits the internal-combustion engine from starting. Since identification code data that cannot be created in a pseudo manner is inputted to the internal-combustion engine control unit, not a binary signal indicating whether to permit or not permit the starting of the internal-combustion engine, the vehicle can be reliably prevented from being burgled and driven away.

TECHNICAL FIELD

The present invention relates to an anti-theft device for a vehicle, andmore particularly to a device for preventing a vehicle from being drivenaway by a burglar.

BACKGROUND ART

There are various methods for preventing vehicle theft such as a methodfor preventing a vehicle from being burgled, a method for disabling avehicle from steering by locking a steering wheel, and a method fordisabling an internal-combustion engine from starting. In the method forpreventing the vehicle from being burgled, an attempt to burgle thevehicle by prying a door or breaking a window is detected using, forexample, a broken window detector or the like, to prevent the burglaryby sounding an alarm, however, once the door is opened, the vehicle canbe easily driven away by the burglar.

The method for disabling an internal-combustion engine from starting iseffective in preventing a vehicle from being burgled and driven. A firstprior art of such method is disclosed, for example, in JapaneseUnexamined Patent Publication JP-A 4-11544 (1992). This prior art ischaracterized in that an anti-theft computer performs control so that arelay interposed in an ignition coil line is deenergized to inhibit theinternal-combustion engine from starting.

A second prior art method is disclosed in Japanese Unexamined PatentPublication JP-A 4-331647 (1992). This prior art method uses ananti-theft control unit which operates to deenergize a relay interposedin a power supply line from the battery to the load and thereby inhibitthe internal-combustion engine from starting.

Thus these two prior art methods disable the internal-combustion enginefrom starting by deenergizing the relay inserted in the load line. Thesemethods, therefore, require a large-size expensive relay, andparticularly in the case of the first prior art, an expensivehigh-voltage relay that can be inserted in an ignition coil line,resulting in an increase in cost. Furthermore, persons experienced invehicle electronics would be able to easily defeat the anti-theftfunction by short-circuiting the input and output of the relay.

A third prior art method that overcomes these problems is disclosed inJapanese Unexamined Patent Publication JP-A 63-284054(1988). In thisprior art, the internal-combustion engine is stopped if a gear shiftoperation is performed without a person's sitting on the driver's seatwhich is folded backward or without entering an identification code.

A fourth prior art method is disclosed in Japanese Unexamined PatentPublication JP-A 2-164648 (1990). This prior art is intended to preventvehicle theft in case the driver forgot to remove the ignition key; thatis, after a predetermined time has elapsed from the time theinternal-combustion engine was stopped, the internal-combustion enginecan be started only when a correct password is entered.

Thus, the third and fourth prior art methods do not require inserting arelay or the like in an aftermarket fashion in an originally installedinternal-combustion engine control unit, etc. as in the first and secondprior art, but are designed to stop the control operation of the controlunit itself.

However, neither the third nor the fourth prior art provides specificdetails about the method of stopping the internal-combustion engineafter detecting a theft, though detailed explanations are given aboutthe detection of the theft. Accordingly, the third and fourth prior artmay also involve the same problems as described in connection with thefirst and second prior art. The present invention, on the other hand, isintended to prevent theft reliably by proposing a specific configurationfor stopping the internal-combustion engine when a theft is detected.

Furthermore, both the third and fourth prior art methods use a dedicatedmicrocomputer for verifying the identification code, the configurationbeing such that only when the identification code has been verified, themicrocomputer sends a binary signal to an internal-combustion enginecontrol computer to permit the internal-combustion engine to start.Therefore, persons experienced in vehicle electronics would be able tostart the internal-combustion engine by creating the binary permitsignal in a pseudo manner, such as by connecting the line fortransmitting the permit signal, for example, to the Vcc line of 5 V orto the grounding line.

Further, in the case of a configuration where the identification code istransmitted from a transmitter, the identification code in the receiveror identifying means must be made rewritable so that it can be used witha new transmitter in case the original transmitter is lost or damaged. Afifth prior art is disclosed in Japanese Unexamined Patent PublicationJP-A 3-70299 (1991) previously proposed by the present applicant. Inthis prior art, switching between an identification code write operationand read operation is made depending on the time that a switch on thereceiver is being operated.

A sixth prior art that also makes the identification code rewritable isdisclosed in Japanese Unexamined Patent Publication JP-A 5-106375(1993). This prior art enables the identification code to be altered byan input operation from an input section when the ignition switch isturned on.

Accordingly, the fifth prior art requires the provision of a switch tomake the identification code rewritable, while the sixth prior art posesa problem in that the identification code can be easily altered.

It is an object of the present invention to provide a vehicle anti-theftdevice that can prevent vehicle theft reliably.

It is another object of the invention to provide a vehicle anti-theftdevice wherein rewriting of the identification code can be accomplishedusing a simple construction and with reliability.

SUMMARY OF THE INVENTION

The invention provides an anti-theft device for a vehicle, comprising:

a control means for controlling operating conditions of aninternal-combustion engine;

a power supply means for stabilizing power from a battery and supplyingthe power to the control means; and

a detection means for making the power supply means stop a function ofpower supply to the control means when a theft of the vehicle isdetected.

The invention is characterized in that:

a short-circuiting means is interposed between a power supply line fromthe power supply means to the control means and a grounding line;

the detection means short-circuits the short-circuiting means when atheft is detected; and

the power supply means stops the function of power supply to the controlmeans by an overcurrent resulting from the short-circuiting.

The invention also provides an anti-theft device for a vehicle,comprising:

a control means for controlling operating conditions of aninternal-combustion engine;

an initializing means provided in relation to the control means, forinitializing the control means at the time when a supply voltage risesand for making calculation of control amounts possible; and

a detection means for inhibiting the initialization of the control meansby the initializing means when a theft of the vehicle is detected.

The invention also provides an anti-theft device for a vehicle,comprising:

a control means for controlling at least either fuel injection quantityor ignition timing of an internal-combustion engine;

a detection means for making the control means stop outputting of atleast either of an injection signal and an ignition signal to theinternal-combustion engine, when a theft of the vehicle is detected.

The invention also provides an anti-theft device for a vehicle,comprising:

a control means for controlling at least either fuel injection quantityor ignition timing of an internal-combustion engine;

a backup control means provided in relation to the control means, forsupplying a fixed backup injection signal or a fixed backup ignitionsignal to the internal-combustion engine when it is detected that aninjection signal or an ignition signal to the internal-combustion enginehas stopped; and

a detection means for detecting a theft of the vehicle, wherein, whenthe theft is detected by the detection means, the control means shortensat least either the injection signal or the ignition signal to apredetermined infinitesimal time.

The invention is characterized in that the control means performs theshortening of the injection signal or the ignition signal when vehiclespeed reaches or exceeds a predetermined value after detection of thetheft of the vehicle.

The invention also provides an anti-theft device for a vehicle,comprising:

a detector provided in relation to an internal-combustion engine, fordetecting control parameters of the internal-combustion engine;

a control means for calculating a control amount based on a detectionresult from the detector, and for supplying a control output to theinternal-combustion engine;

a detection means for detecting a theft of the vehicle; and

a shut-off means interposed between the detector and the control means,for shutting off an output from the detector when the theft is detectedby the detection means.

The invention also provides an anti-theft device for a vehicle,comprising:

a detector provided in relation to an internal-combustion engine, fordetecting control parameters of the internal-combustion engine;

a control means for calculating a control amount based on a detectionresult from the detector, and for supplying a control output to theinternal-combustion engine;

a detection means for detecting a theft of the vehicle; and

a shut-off means interposed in a power supply line to the detector, forshutting off the power supply line when the theft is detected by thedetection means.

The invention is characterized in that the detection means transmits thedetection result in the form of a code signal.

The invention also provides an anti-theft device for a vehicle,comprising:

a control means for controlling operating conditions of aninternal-combustion engine;

a storage means having a storage area for data relating to the controlof the operating conditions of the internal-combustion engine and astorage area for an identification code; and

an input means to which an identification code is inputted by apredetermined operation,

wherein, when energization of the control means is started with anattempt to start the internal-combustion engine, the control meanscompares the identification code inputted from the input means with theidentification code stored in the storage means, and when they do notcoincide, the control means inhibits the internal-combustion engine fromstarting.

The invention is characterized in that the comparison operation isperformed again when a rotational speed of the internal-combustionengine is not higher than a predetermined value, a vehicle speed is nothigher than a predetermined value, and a shift lever of a transmissionis in a parking or neutral position.

The invention is also characterized in that, when a vehicle speed is notlower than a predetermined value, starting of the internal-combustionengine is permitted regardless of a result of the comparison between theidentification codes.

The invention is also characterized in that, when parameters to be usedto control the internal-combustion engine are inputted in a combinationthat cannot occur during a usual operation of the internal-combustionengine, the control means writes the identification code inputted to theinput means, into the storage means.

According to the invention, a detection means for detecting vehicletheft is provided in relation to control means for controllinginternal-combustion engine operating conditions such as fuel injectionquantity and ignition timing. Power from a battery is stabilized bypower supply means and supplied to the control means. Upon detecting atheft, for example, when an attempt is made to start theinternal-combustion engine despite a dissidence between the prestoredidentification code of the vehicle and the input identification codesuch as a password, the detection means makes the power supply meansstop the supply of power to the control means.

More specifically, the power supply means performs so-calledconstant-voltage control by controlling the base current of atransistor, inserted in series to the power line from the battery to thecontrol means, in proportion to an output voltage of the transistor.Accordingly, when a vehicle theft is detected, power supply to thecontrol means ceases. In this way, vehicle theft can be reliablyprevented without requiring a large-size component such as a relay.

Preferably, a short-circuiting means is interposed between the powersupply line from the power supply means to the control means and thegrounding line, and the detection means causes the short-circuitingmeans to activate upon detection of a theft. To protect the power supplymeans from the overcurrent resulting from the short-circuiting, thepower supply means cuts off the base current of the transistor, forexample, and the power to the control means is thus cut off. In thisway, the power supply function can be disabled using a simpleconstruction by just providing short-circuiting means.

Furthermore, according to the invention, an initializing means isprovided in relation to the control means. The initializing meansinitializes the control means by supplying an initialization signal orthe like to the control means when the supply voltage rises, and thecalculation of control amounts such as the fuel injection quantity andignition timing is thus made possible. When a vehicle theft is detected,the detection means inhibits the initialization of the control means bythe initializing means. Accordingly, when a theft is detected, thecontrol means cannot perform the calculation of the control amounts evenafter the supply voltage has risen. Vehicle theft can thus be preventedreliably.

According to the invention, when a theft is detected by the detectionmeans, the control means for controlling at least either the fuelinjection quantity or ignition timing of the internal-combustion engineis made to stop an output of at least either the injection signal or theignition signal to the internal-combustion engine.

Furthermore, according to the invention, a backup control means isprovided in addition to the control means that controls at least eitherthe fuel injection quantity or ignition timing of theinternal-combustion engine. In the event of a failure of the controlmeans or at the time of staring with low voltage, for example, thebackup control means controls the fuel injection quantity and ignitiontiming to predetermined fixed values, permitting emergency driving, etc.to a repair shop. The backup control means supplies a backup injectionsignal or backup ignition signal to the internal-combustion engine whenit is detected that the output of the injection signal or ignitionsignal from the control means to the internal-combustion engine hasstopped.

When a vehicle theft is detected by the detection means, the controlmeans shortens at least either the injection signal or the ignitionsignal to a predetermined infinitesimal time. Accordingly, since theinjection signal or ignition signal from the control means is notcompletely stopped, the backup control means does not output the backupinjection signal or backup ignition signal; furthermore, when theinjection signal or ignition signal is shortened to an infinitesimaltime, as described above, the air-fuel mixture in the combustion chamberdoes not ignite. In this way, vehicle theft can be prevented reliably.

Preferably, the control means uses vehicle speed as a criterion forshortening the injection signal or ignition signal; that is, when thevehicle speed reaches or exceeds a predetermined value after detectionof the vehicle theft, the control means performs the shorteningoperation. In this way, the anti-theft action can be put into operationonly when the vehicle being stolen is started to be driven away.

According to the invention, in an internal-combustion engine controlunit in which control parameters such as intake pressure andinternal-combustion engine rotating speed are detected by a detectorand, based on the detection results, a control means performscalculation of control amounts, detection means for detecting vehicletheft is provided, and when a theft is detected by the detection means,shut-off means, such as a switch interposed between the detector and thecontrol means, is shut off. Since the detector output is not inputted tothe control means, the control means cannot calculate the controlamounts and the internal-combustion engine cannot be started. Vehicletheft can thus be prevented reliably.

Furthermore, according to the invention, the shut-off means is insertedin the power supply line to the detector, and calculation of the controlamounts is rendered impossible by disabling the detector output bystopping the power supply from the power source.

Also preferably, the result of the detection as to whether the vehicleis being stolen or not is sent to the control means or theshort-circuiting means in the form of a code signal. It is therefore notpossible to reproduce such a code signal by simply setting the line fromthe detection means to the control means or the short-circuiting meansto a high level or low level, attempting to input the result of thedetection in a pseudo manner. In this way, vehicle theft can beprevented further reliably.

According to the invention, an input means is provided in relation to acontrol means provided for controlling internal-combustion engineoperating conditions such as fuel injection quantity and ignitiontiming. An identification code is inputted to the input means, forexample, as a signal from a special transmitter or by a predeterminedkey operation. Also provided in relation to the control means is storagemeans for storing data relating to the control of theinternal-combustion engine operating conditions, such as map data ofinjection quantity corresponding to the measured intake pressure,internal-combustion engine rotational speed, etc. This storage means hasan identification code storage area in addition to a storage area forthe above data.

When energization of the control means is started, that is, when theignition key is connected, for example, to a start contact to start theinternal-combustion engine, the control means compares theidentification code inputted via the input means with the identificationcode stored in the storage means, and when they coincide, permits thestarting of the internal-combustion engine, allowing theinternal-combustion engine to be started by energizing the startermotor, for example. On the other hand, when the identification codes donot coincide, starting of the internal-combustion engine is inhibited,for example, by stopping fuel injection or by disabling the output ofthe ignition signal.

Not a binary signal indicating whether to permit or not permitinternal-combustion engine starting as described in the prior art, butan identification code is inputted to the control unit and compared withthe identification code stored in the storage means provided in relationto the control unit. Accordingly, it is not possible even for personsexperienced in vehicle electronics to create a pseudo signalcorresponding to the identification code. In this way, when theidentification codes do not coincide, starting of theinternal-combustion engine is reliably inhibited to prevent the theft.

Preferably, the control means performs the comparing operation againwhen the rotational speed of the internal-combustion engine is nothigher than a predetermined value, for example, 800 rpm, the vehiclespeed is at a predetermined value, for example, 0 km/h, and the shiftlever of the transmission is in the neutral or parking position.Therefore, even if an erroneous decision was made and the starting ofthe internal-combustion engine was not permitted during the operation tostart the internal-combustion engine, the internal-combustion engine canbe started if the identification codes coincide as a result of therejudgement in the state where the above-mentioned conditions aresatisfied. The fail-safe function can thus be expanded.

Also preferably, when the vehicle speed is higher than a predeterminedvalue, the control means permits the starting of the internal-combustionengine regardless of the result of the comparison of the identificationcodes, allowing the internal-combustion engine to be restarted quicklyin the event of an internal-combustion engine stall during driving.

Further preferably, when parameters to be used to control theinternal-combustion engine are inputted in a combination that cannotoccur during usual operation of the internal-combustion engine, forexample, when such states that the neutral switch is in the OFF state,namely the vehicle is in a running state, and the starter signal is atthe high level, namely the starter motor is being driven are simulatedand parameters representing such conditions are inputted to the controlmeans, the control means writes the identification code inputted to theinput means, directly to the storage means.

In this way, rewriting of the identification code, which becomesnecessary, for example, when the transmitter is lost, can beaccomplished using a simple construction without having to provide aswitch or the like on the control means. Furthermore, since inadvertentrewriting is prevented, vehicle theft can be prevented reliably.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing the electrical configuration of avehicle control device 1 equipped with an anti-theft function of oneembodiment of the present invention;

FIG. 2 is an electric circuit diagram showing a detailed configurationof a constant-voltage circuit 67;

FIG. 3 is an electric circuit diagram showing a constant-voltage circuit67a of another embodiment of the invention;

FIG. 4 is an electric circuit diagram showing a constant-voltage circuit67b of another embodiment of the invention;

FIG. 5 is a waveform diagram for explaining the operation of theembodiment shown in FIG. 4;

FIG. 6 is a block diagram showing the electrical configuration of avehicle control device Ill of another embodiment of the invention;

FIG. 7 is a waveform diagram for explaining the operation of the vehiclecontrol device 111;

FIG. 8 is a flowchart for explaining a main processing routine for thevehicle control device 111;

FIG. 9 is a flowchart for explaining an interrupt handling routine forthe vehicle control device 111;

FIG. 10 is a block diagram showing the electrical configuration of aninternal-combustion engine control unit 3b of still another embodimentof the invention;

FIG. 11 is an electric circuit diagram showing a detailed configurationof an input interface circuit 17a of another embodiment of theinvention;

FIG. 12 is a flowchart for explaining the operation of still anotherembodiment of the invention;

FIG. 13 is a block diagram showing the configuration of aninternal-combustion engine control unit 3c of another embodiment of theinvention and an intake pressure detector 11a used with the same;

FIG. 14 is a block diagram showing the electrical configuration of avehicle control device 1 equipped with an anti-theft function of anotherembodiment of the invention;

FIG. 15 is a timing chart for explaining the theft prevention operation;

FIG. 16 is a flowchart for FIG. 15;

FIG. 17 is a flowchart for explaining a theft prevention operation ofanother embodiment of the invention; and

FIG. 18 is a flowchart for explaining a write operation ofidentification data.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a block diagram showing the electrical configuration of avehicle control device 1 equipped with an anti-theft function of oneembodiment of the invention. The vehicle control device 1 substantiallycomprises an internal-combustion engine control unit 3 for controllingan internal-combustion engine 2, an automatic transmission control unit5 for controlling an automatic transmission 4, and a door lock controlunit 6.

Substantially, the internal-combustion engine control unit 3 computesfuel injection quantity and ignition timing based on the intake pressureof the internal-combustion engine 2 detected by an intake pressuredetector 11, and the rotational speed of the internal-combustion engine2 detected by a crank angle detector 12, etc., and thereby drives a fuelinjection valve 13 and an igniter 14. The internal-combustion enginecontrol unit 3 comprises input interface circuits 16 to 19, ananalog/digital converter 8, a processing circuit 7 implemented by amicrocomputer, etc., a memory 20 implemented by an erasable rewritableread-only memory such as a so-called EEPROM or the like, and an outputinterface circuit 21.

An output from the intake pressure detector 11 is converted by theanalog/digital converter 8 into a digital value, which is read into theprocessing circuit 7. A crank pulse from the crank angle detector 12 isinputted to the processing circuit 7 after waveform-shaping in the inputinterface circuit 17. The input interface 16 is provided to receive asignal from the automatic transmission control unit 5.

Outputs from a neutral switch 9 and a start switch 10 also are inputtedto the processing circuit 7 after waveform-shaping in the respectiveinput interface circuits 18 and 19. The neutral switch 9 conducts whenthe shift lever of the automatic transmission 4 is in the parking orneutral position. The starter switch 10 conducts while the starter motoris being driven.

Based on the detection results from the switches 9, 10 and the detectors11, 12, the signal from the automatic transmission control unit 5, etc.,the processing circuit 7 computes the fuel injection quantity, ignitiontiming, etc. by referencing map data, etc. stored in the memory 20, andthereby controls the ignition timing and ignition time of a spark plug23 via the igniter 14 and also the valve opening time of the fuelinjection valve 13 via the output interface circuit 21 implemented by apower transistor, etc.

Essentially, the automatic transmission control unit 5 selectivelydrives a solenoid valve 28 in the automatic transmission 4 in responseto the detection results from a throttle valve opening detector 25, avehicle speed detector 26, and a shift position detector 27, andtransmits the drive force from the internal-combustion engine 2 to adrive wheel 29 after reduction by a desired reduction ratio. Theautomatic transmission control unit 5 comprises input interface circuits30 and 31, an analog/digital converter 32, a processing circuit 33, amemory 34, and output interface circuits 35 and 36.

The vehicle speed detector 26 detects the rotational speed of apropeller shaft 37. Speed pulses from the vehicle speed detector 26 arewaveform-shaped in the input interface circuit 31, and then inputted tothe processing circuit 33 implemented by a microcomputer, etc. The shiftposition of the automatic transmission 4 is read by the shift positiondetector 27, and is inputted to the processing circuit 33 via the inputinterface circuit 30. The detection result from the throttle valveopening detector 25, which, is implemented using a potentiometer or thelike, is converted by the analog/digital converter 32 into a digitalvalue, which is inputted to the processing circuit 33.

Based on the shift position detected by the shift position detector 27,the throttle valve opening detected by the throttle valve openingdetector 25, and the vehicle speed detected by the vehicle speeddetector 26, the processing circuit 33 reads optimum gear from shiftmaps stored in the memory 34 implemented by a read-only memory or thelike, and performs control to select the appropriate solenoid valve 28via the output interface circuit 35 implemented by a power transistor,etc. to achieve shifting into the desired gear.

The processing circuit 33 supplies the previously mentioned signal tothe input interface circuit 16 in the internal-combustion engine controlunit 3 through the output interface circuit 36 and a line 38. Thissignal represents the vehicle speed and shift timing. Theinternal-combustion engine control unit 3 reduces shift shocks, forexample, by temporarily delaying the ignition timing in coordinationwith the shift timing.

The door lock control unit 6 includes a receiver 42 which drives a doorlock actuator 43 in response to a signal from a transmitter 41. When atheft is detected by a switch 44 or 45, the receiver 42 performs ananti-theft action by sounding a horn 46 and flashing a stop signalindicator light 47 at the same time.

The transmitter 41 comprises a pushbutton switch 51, a transmittingcircuit 52, and a memory 53. When the pushbutton switch 51 is operated,the transmitting circuit 52 reads the identification code unique to thetransmitter 41 from the memory 53 implemented by a read-only memory orthe like, and transmits a signal representing the identification code tothe receiver 42 via a frequency- or amplitude-modulated wave or viainfrared light.

The receiver 42 comprises a receiving circuit 54, input interfacecircuits 55 to 58, a processing circuit 50, a memory 60, and outputinterface circuits s61 and 62. The signal representing theidentification code and received by the receiving circuit 54 iswaveform-shaped in the input interface circuit 55 before being inputtedto the processing circuit 50 implemented by a microcomputer, etc. Theprocessing circuit 50 determines whether the identification code matchesthe identification code of the vehicle stored in the memory 60implemented by a read-only memory or the like, and when they coincide,drives through the output interface circuit 61 the actuator 43implemented by an electromagnetic solenoid or the like. That is, whenthe doors and trunk are in locked position, an unlocking operation isperformed, and when they are in unlocked position, a locking operationis performed.

Outputs from the switches 63, 44, and 45, with chattering componentsremoved by the respective input interface circuits 56, 57, and 58, areinputted to the processing circuit 50. With the set switch 63 conductingand thus activating the anti-theft function, when the opening of thehood or door is detected by the hood switch 44 for detecting theopening/closing of the internal-combustion engine hood or by thecourtesy switch 45 for detecting the opening/closing of the door, theprocessing circuit 50 sounds the horn 46 while flashing the stop signalindicator light 47, in the same manner as previously described, thusperforming the theft prevention operation.

When a theft is detected, as will be described later, the processingcircuit 50 also outputs a code signal indicating the detection of theftto a constant-voltage circuit 67 in the internal-combustion enginecontrol unit 3 through the output interface circuit 62 and via a line64.

The control units 3, 5, and 6 are also provided with constant-voltagecircuits 67, 68, and 69, respectively. When an ignition key switch 65 isconnected to an IG contact or ST contact, power from a battery 66 issupplied to the constant-voltage circuits 67 and 68 to energize thecircuits in the control units 3 and 5. Power from the battery 66 isconstantly supplied to the constant-voltage circuit 69 to energize thecircuits in the receiver 42 in the door lock control unit 6.

FIG. 2 is an electric circuit diagram showing the detailed configurationof the constant-voltage circuit 67. The constant-voltage circuit 67comprises a transistor 72 inserted in series in a power supply line 71from the ignition key switch 65 to the respective circuits in theinternal-combustion engine control unit 3, a constant-voltage controlblock 73 for controlling the base current of the transistor 72, and areceiver 74 for decoding the code signal indicating the result of theftdetection from the door lock control unit 6, and for supplying an outputcorresponding to the result of the detection to the constant-voltagecontrol block 73.

The constant-voltage control block 73 is implemented by an integratedcircuit or the like, and comprises: a resistor 75 and a Zener diode 76,interposed between the power supply line 71 and grounding line, forcreating a reference voltage; a comparator 77 for comparing the supplyvoltage to the circuits in the internal-combustion engine control unit3, which is applied from the power supply line 70 via a line 78, withthe reference voltage which is inputted from a node between the resistor75 and Zener diode 76 and controlling the base current of the transistor72 in correspondence to the comparison results ; and a transistor 79inserted in parallel with the Zener diode 76.

When the code signal indicating a vehicle theft is inputted to thereceiver 74 via the line 64 from the output interface circuit 62 in thedoor lock control unit 6, the receiver 74 produces a high level outputwhich is applied to the base of the transistor 79. This causes thetransistor 79 to conduct, as a result of which the reference voltageinput from the node between the resistor 75 and Zener diode 76 to thecomparator 77 becomes nearly equal to ground potential. The comparator77 thus stops sinking the base current of the transistor 72, cutting offpower supply to the circuits in the internal-combustion engine controlunit 3.

On the other hand, when no theft is detected, the receiver 74 produces alow level output, causing the transistor 79 to turn off, so that thecomparator 77 sinks the base current of the transistor 72 incorrespondence to the difference between the reference voltage, obtainedby tapping the power supply line 71, and the supply voltage to therespective circuits, and supplies a desired voltage, for example, aconstant voltage of 5 V, to the respective circuits.

By cutting off power supply to the circuits in the internal-combustionengine control unit 3 upon detection of a theft, as described above, theoutput of an injection signal to the fuel injection valve 13 and theoutput of an ignition signal to the igniter 14 are stopped, thusreliably inhibiting the internal-combustion engine 2 from starting.

Furthermore, since the result of the detection as to whether the vehicleis being stolen or not is inputted in the form of a code signal from thedoor lock control unit 6 to the constant-voltage circuit 67, it is notpossible to reproduce the code signal by simply setting the line 64 to ahigh level or low level, attempting to input a code signal in a pseudomanner. This further ensures the effectiveness of the theft prevention.

FIG. 3 is an electric circuit diagram showing a constant-voltage circuit67a according to another embodiment of the invention. This circuit issimilar to the constant-voltage circuit 67, and corresponding parts aredesignated by the same reference numerals. The constant-voltage circuit67a is characterized by the provision of a constant current controlblock 81 and a muting circuit 82 in addition to the constant-voltagecontrol block 73a. The constant current control block 81 comprises ashunt resistor 83 inserted in the power supply line 71, a pair oftransistors 84 and 85 forming a current mirror circuit, aconstant-voltage source 86, and a constant current source 87. Theterminal voltages of the shunt resistor 83 are applied to the respectiveemitters of the transistors 84 and 85. The constant-voltage source 86 isinterposed between the emitter of the transistor 84 and the shuntresistor 83. The base and collector of the transistor 85 are groundedvia the constant current source 87, while the collector of thetransistor 84 is connected to the base of the transistor 72.

Accordingly, when the current passing through the shunt resistor 83increases, and the voltage drop across the shunt resistor 83 exceeds thevoltage across the constant-voltage source 86, for example, 250 mV, thecurrent flowing through the transistor 84 becomes larger than thecollector current of the transistor 85 regulated by the constant currentsource 87, as a result of which the amount of sinking of the basecurrent of the transistor 72 by the comparator 77 decreases and thetransistor 72 is turned off. In this way, the constant current controlblock 81 has the function of stopping the power supply to the respectivecircuits when an overcurrent occurs.

On the other hand, the muting circuit 82 comprises a transistor 88 andresistors 89 to 91. The output of the receiver 74 is coupled to the baseof the transistor 88 via the voltage-dividing resistors 89 and 90. Thecollector of the transistor 88 is connected to the power supply line 70via the current-limiting resistor 91, while the emitter thereof isgrounded.

Accordingly, when the code signal indicating the detection of theft isreceived from the door lock control unit 6, the receiver 74 produces ahigh level output by which the transistor 88 conducts and the current tobe supplied to the respective circuits in the internal-combustion enginecontrol unit 3 via the power supply line 70 is cut off. At the sametime, the constant current control block 81 detects an overcurrent andthe transistor 72 is turned off, thus reliably cutting the power supplyto the respective circuits. Starting of the internal-combustion engine 2can thus be prevented with simple construction by using the overcurrentdetection function of the constant current control block 81.

FIG. 4 is an electric circuit diagram showing a constant-voltage circuit67b according to still another embodiment of the invention. Theconstant-voltage circuit 67b comprises the constant-voltage controlblock 73a and an initializing circuit 101 as an example of aninitializing means. The initializing circuit 101 comprises a comparator104, transistors 105 and 106, resistors 107 and 108, and a referencevoltage source 109.

The voltage to be supplied to the respective circuits such as theprocessing circuit 7 in the internal-combustion engine control unit 3 isapplied to the noninverting input terminal of the comparator 104 fromthe collector of the transistor 72 via the line 70. On the other hand,the voltage of the power supply line 71 is applied through the inputresistor 107 to the inverting input terminal of the comparator 104 whichis also supplied with a reference voltage Vref from the referencevoltage source 109, the reference voltage being sufficiently lower thanthe voltage of the power supply line 71 when the ignition key switch 65is conducting. When the voltage at the inverting input terminal ishigher than the voltage at the noninverting input terminal, thecomparator 104 produces a high level output and applies to the base ofthe transistor 105. The transistor 105 is connected to the power supplyline 70 via the pull-up resistor 108 and also to an initializingterminal INIT on the processing circuit 7. Connected in parallel withthe transistor 105 is the transistor 106 which is controlled to conductor turn off by an output from the receiver 74. When the initializingterminal INIT is at a high level, the processing circuit 7 is enabled toperform computations.

In the above-configured constant-voltage circuit 67b, when the voltageof the power supply line 71 varies as shown by reference signal in FIG.5(1), the voltage of the power supply line 70 varies as shown byreference sign a2. That is, when the power supply line 71 is at apredetermined voltage V1, the voltage of the power supply line 70 isstabilized at V2. When the voltage of the power supply line 71 drops,and the voltage of the power supply line 70 drops below the referencevoltage Vref supplied from the reference voltage source 109, thecomparator 104 produces a high level output, causing the transistor 105to conduct. As a result, the initializing terminal INIT on theprocessing circuit 7 is brought to a low level, and the operation of theprocessing circuit 7 stops.

Even when the voltage of the power supply line 71 rises nearly to thevoltage V1, if the receiver 74 is producing a high level outputindicating the detection of a theft, as shown in FIG. 5(2), thetransistor 106 conducts and the potential of the initializing terminalINIT is held at the low level.

In this way, upon detection of a theft, the internal-combustion engine 2can be prevented from being started by inhibiting the initializingoperation of the processing circuit 7 and rendering the calculation ofcontrol amounts impossible.

FIG. 6 is a block diagram showing the electrical configuration of avehicle control device 111 according to another embodiment of theinvention. This embodiment is similar to the foregoing embodiment, andcorresponding parts are designated by the same reference numerals. Thisembodiment is characterized in that the code signal indicating theresult of theft detection, which is outputted from the output interfacecircuit 62 in the door lock control unit 6 via the line 64, is inputtedto the processing circuit 7 in the internal-combustion engine controlunit 3a via the input interface circuit 15.

For this purpose, an output interface circuit 22 is provided in theinternal-combustion engine control unit 3a and an input interface unit6. More specifically, when a transmit request is outputted from theprocessing circuit 7 via the output interface circuit 22, the processingcircuit 50 receives the transmit request via the input interface circuit59, and outputs the code signal, as described above.

When no theft is detected from the thus received code signal, a flag Findicating whether a theft is detected or not is reset to 0, and theprocessing circuit 7 calculates the fuel injection quantity based on theintake pressure, the rotational speed of the internal-combustion engine2, etc., as previously described, and outputs an injection signal sothat the fuel injection valve 13 is opened for a time corresponding tothe calculated result. On the other hand, when a theft is detected, theflag F is set to 1, and the time of the injection signal is shortened toa predetermined fixed value.

More specifically, when the internal-combustion engine 2 is afour-cylinder, four-cycle internal-combustion engine, for example, acrank pulse such as shown in FIG. 7(1) is inputted to the processingcircuit 7 for every cycle of 180° crank angle. In FIG. 7(1), the cycleis indicated by reference sign T1. Based on the cycle T1, the intakepressure detected by the intake pressure detector 11, etc., theprocessing circuit 7 calculates the fuel injection quantity and fuelinjection timing by referencing the map data, etc. stored in the memory20. In accordance with the thus obtained injection quantity andinjection timing, valve opening time T2 and time T3 measured from thenearest rising timing of the crank pulse are determined, and aninjection signal that changes as shown in FIG. 7(3) is outputted whenthe respective times have elapsed from the rising timing. On the otherhand, when a theft is detected, the valve opening time T2 is set to 0.

The injection signal shown in FIG. 7(3) is an example of the injectionsignal for the so-called simultaneous injection manner in which only onefuel injection valve 13 is provided in the internal-combustion engine 2for common delivery of fuel into all cylinders. Accordingly, in the caseof the so-called individual injection system in which the fuel injectionvalve 13 is provided for each individual cylinder, the fuel injectionsignal is sequentially outputted in correspondence with the cylindernumbers shown in FIG. 7(2).

FIGS. 8 and 9 are flowcharts for explaining the operation shown in FIG.7. FIG. 8 shows a main processing routine for the processing circuit 7.In step n1, initialization is performed, including resetting the flag F.In step n2, a transmit request for the code signal is issued to the doorlock control unit 6, and in step n3, the code signal transmitted inresponse to the transmit request is read. In step n4, it is determinedwhether or not the code signal indicates the detection of a theft. Whenno theft is detected, the flag F is reset to 0 in step n5, and then theprocess proceeds to step n6; on the other hand, when a theft isdetected, the flag F is set to 1 in step n7, and then the processproceeds to step n6.

In step n6, fuel injection quantity is determined from the flag F resetor set in step n5 or n7, the intake pressure, the internal-combustionengine rotational speed, etc. After determining the ignition timing instep n8, the process proceeds to other processing such as a fail-safeoperation.

FIG. 9 is a flowchart for explaining an interruption process whichoccurs at the rising edge of the crank pulse. In step m1, it isdetermined whether the flag F is set to 1 or not, and if not, the timesT2 and T3 corresponding to the calculated result obtained in step n6 areset in a timer in step m2, and then the process proceeds to step m3. Onthe other hand, if the flag F is set, the process jumps to step m3without performing the setting of the timer. In step m3, a timer is setfor the ignition timing, after which the process returns to the mainroutine shown in FIG. 8.

In the above embodiment, the valve opening time T2 of the injectionsignal is set to 0 when a theft is detected. On the other hand, FIG. 10shows an internal-combustion engine control unit 3b according to yetanother embodiment of the invention, in which a backup integratedcircuit 112 is provided in relation to the processing circuit 7; whenthe internal-combustion engine 2 is being started at low temperatures,when the voltage of the battery 66 has dropped, or when the processingcircuit 7 has run away out of control, a detection circuit 117 providedin the processing circuit 7 identifies such a condition, and produces anoutput to the backup integrated circuit 112 which, in response to theoutput, outputs a fixed backup injection signal and backup ignitionsignal to the fuel injection valve 13 and the igniter 14 respectivelythrough switches 113 and 114 instead of the injection signal andignition signal output from the processing circuit 7. In thisconstruction, if the injection signal is dropped as illustrated in theforegoing embodiment, the backup integrated circuit 112 will beactivated.

In such a case, instead of setting the valve opening time T2 to 0 as inthe foregoing embodiment, the valve opening time T2 may be chosen shortenough that the backup integrated circuit 112 is not activated and thatthe air-fuel ratio becomes large enough so as not to ignite the air-fuelmixture in the internal-combustion engine 2. This serves to avoid anerroneous activation of the backup operation, and reliably prevents theinternal-combustion engine 2 from being started.

As another embodiment of the invention, provisions may be made to stopthe output of the ignition signal of FIG. 7(4) that is outputted inresponse to the crank pulses of FIG. 7(1), or the rising time T4 of theignition signal may be chosen extremely short to prevent the spark plug23 from igniting the air-fuel mixture. Alternatively, provisions may bemade not to set time T5 in a timer in which T5 should otherwise be set,where T5 is the length of time from the rising of the crank pulse to therising of the ignition signal.

FIG. 11 is an electric circuit diagram showing an input interfacecircuit 17a according to another embodiment of the invention. The inputinterface circuit 17a comprises a waveform shaping circuit 121 and amuting circuit 122. A crank pulse from a magnet pickup 12a in the crankangle detector 12 is inputted to a comparator 123 via a filter circuitconsisting of resistors 128 to 130 and capacitors 126 and 127. Theoutput terminal of the comparator 123 is connected to the processingcircuit 7, to the power supply line 70 via a pull-up resistor 132, to aninput terminal via a feedback resistor 133, and also to ground via themuting circuit 122.

When the detection result indicating the detection of theft is receivedby the receiver 74, the muting circuit 122 conducts to provide a bypassfor the crank pulse which should otherwise be inputted from thecomparator 123 to the processing circuit 7. An input line 134 from themagnet pickup 12a is connected to the power supply line 70 via a pull-upresistor 131 to be pulled-up so as to prevent a negative surge frombeing inputted to the comparator 123. In relation to the line 134, thereare also provided a Zener diode 124 for overvoltage protection and adiode 125 for negative surge absorption.

Accordingly, in the above-mentioned configuration, when a theft isdetected, since input of the crank pulse from the input interfacecircuit 17a to the processing circuit is inhibited, the starting of theengine 2 can be thus prevented.

Alternatively, rather than inhibiting the crank pulse from beinginputted to the processing circuit 7 as in the above embodiment,provisions may be made to inhibit the reading of the input crank pulseinto the processing circuit 7 by means of software.

FIG. 12 is a flowchart for explaining the operation of still anotherembodiment of the invention. This embodiment is similar to theembodiment illustrated in connection with FIG. 9. The difference isthat, when setting the injection ON time in relation to the rising ofthe crank pulse, if the flag F is set to 1 in step m1, the processproceeds to step m4, where it is determined whether or not the vehiclespeed inputted from the automatic transmission control unit 5 is equalto or lower than a predetermined value, for example, 5 km/h; if theanswer is YES, the process proceeds to step m2 to set the valve openingtime T2 and injection ON time T3, and if the answer is NO, the processjumps to step m3 without making the above settings.

In this way, the internal-combustion engine 2 can be stopped withcertainty only when the vehicle being stolen is started to be drivenaway.

FIG. 13 is a block diagram showing an internal-combustion engine controlunit 3c according to another embodiment of the invention and an intakepressure detector 11a used in relation to the same. In the embodimentshown in FIG. 11, when a theft is detected, the crank pulse from thecrank angle detector 12 is short-circuited to inhibit the input thereof;in the present embodiment, however, when a theft is detected, the powersupply line to the intake pressure detector 11a is cut off, therebydisabling the detector output.

More specifically, when the code signal indicating the detection of atheft is not received by the receiver 74, the processing circuit 7produces a high level output which is supplied to an output interfacecircuit 142 containing an output transistor, etc. As a result, theoutput transistor conducts, and the output interface circuit 142 sinksan exciting current via a relay coil 144 of a relay 143 connected to thepower supply line 71. This causes a relay switch 145 to conduct, so thatthe voltage derived from a constant-voltage circuit 67c onto the powersupply line 70 is applied to a differential amplifier 146 in the intakepressure detector 11a. In this way, an output from a detector 147implemented by a piezoelectric element, impact resistor, or the like, isamplified by the differential amplifier 146 and inputted to theanalog/digital converter 8 in the internal-combustion engine controlunit 3c.

On the other hand, when a theft is detected, the output from theprocessing circuit 7 to the output interface circuit 142 goes low, as aresult of which the output transistor turns off and the relay switch 145opens to cut off the power supply to the intake pressure detector 11a.It is thus possible to cut off the power supply to the detector.Alternatively, provisions may be made by means of software to inhibitthe reading of the detector output when a theft is detected.

FIG. 14 is a block diagram showing the electrical configuration of avehicle control device 1 equipped with an anti-theft function accordingto another embodiment of the invention. The vehicle control device 1comprises an internal-combustion engine control unit 3 for controllingan internal-combustion engine 2, an automatic transmission control unit5 for controlling an automatic transmission 4, and a door lock controlunit 6.

Essentially, the internal-combustion engine control unit 3 computes fuelinjection quantity and ignition timing based on the intake pressure ofthe internal-combustion engine 2 detected by an intake pressure detector11, the rotational speed of the internal-combustion engine 2 detected bya crank angle detector 12, etc., and thereby drives a fuel injectionvalve 13 and an igniter 14. The internal-combustion engine control unit3 comprises input interface circuits 15 to 19, an analog/digitalconverter 8, a processing circuit 7 implemented by a microcomputer,etc., a memory 20 implemented by an erasable rewritable read-only memorysuch as a so-called EEPROM or the like, and output interface circuits 21and 22.

An output from the intake pressure detector 11 is converted by theanalog/digital converter 8 into a digital value, which is read into theprocessing circuit 7. A crank pulse from the crank angle detector 12 isinputted to the processing circuit 7 after being waveform-shaped in theinput interface circuit 17. The input interface circuit 15 is providedto receive a signal from the door lock control unit 6, while the inputinterface 16 is provided to receive a signal from the automatictransmission control unit 5.

Outputs from a neutral switch 9 and a start switch 10 also are inputtedto the processing circuit 7 after being waveform-shaped in the inputinterface circuits 18 and 19, respectively. The neutral switch 9conducts when the shift lever of the automatic transmission 4 is in theparking or neutral position. The starter switch 10 conducts while thestarter motor is being driven.

Based on the detection results from the switches 9, 10 and the detectors11, 12, the signal from the automatic transmission control unit 5, etc.,the processing circuit 7 computes the fuel injection quantity, ignitiontiming, etc. by referencing map data, etc. stored in a memory area 20aof the memory 20, and thereby controls the valve opening time of thefuel injection valve 13 via the output interface circuit 21 implementedby a power transistor, and also the ignition timing and ignition time ofa spark plug 23 via the igniter 14, etc.

In addition to the memory area 20a, the memory 20 has a memory area 20bin which an identification code is stored.

Essentially, the automatic transmission control unit 5 selectivelydrives a solenoid valve 28 in the automatic transmission 4 in responseto the detection results from a throttle valve opening detector 25, avehicle speed detector 26, and a shift position detector 27, andtransmits the drive force from the internal-combustion engine 2 to adrive wheel 29 after reduction by a desired reduction ratio. Theautomatic transmission control unit 5 comprises input interface circuits30 and 31, an analog/digital converter 32, a processing circuit 33, amemory 34, and output interface circuits 35 and 36.

The vehicle speed detector 26 detects the rotational speed of apropellershaft 37. Speed pulses from the vehicle speed detector 26 arewaveform-shaped in the input interface circuit 31, and then inputted tothe processing circuit 33 implemented by a microcomputer, etc. The shiftlever position of the automatic transmission 4 is read by the shiftposition detector 27, and is inputted to the processing circuit 33 viathe input interface circuit 30. The detection result from the throttlevalve opening detector 25, which is implemented using a potentiometer orthe like, is converted by the analog/digital converter 32 into a digitalvalue, which is inputted to the processing circuit 33.

Based on the shift position detected by the shift position detector 27,the throttle valve opening detected by the throttle valve openingdetector 25, and the vehicle speed detected by the vehicle speeddetector 26, the processing circuit 33 reads optimum gear from shiftmaps stored in the memory 34 implemented by a read-only memory or thelike, and performs control to select the appropriate solenoid valve 28via the output interface circuit 35 implemented by a power transistor,etc. to achieve shifting into the desired gear.

The processing circuit 33 supplies the previously mentioned signal tothe input interface circuit 16 in the internal-combustion engine controlunit 3 through the output interface circuit 36 and a line 38. Thissignal, as will be described later, represents the vehicle speed andshift timing. The internal-combustion engine control unit 3 reducesshift shocks, for example, by temporarily delaying the ignition timingin coordination with the shift timing.

The door lock control unit 6 includes a receiver 42 which essentiallydrives a door lock actuator 43 in response to a signal from atransmitter 41. When a theft is detected by a switch 44 or 45, thereceiver 42 performs an anti-theft action by sounding a horn 46 andflashing a stop signal indicator light 47 at the same time.

The transmitter 41 comprises a pushbutton switch 51, a transmittingcircuit 52, and a memory 53. When the pushbutton switch 51 is operated,the transmitting circuit 52 reads the identification code unique to thetransmitter 41 from the memory 53 implemented by a read-only memory orthe like, and transmits a signal representing the identification code tothe receiver 42 via a frequency- or amplitude-modulated wave or viainfrared light.

The receiver 42 comprises a receiving circuit 54, input interfacecircuits 55 to 59, a processing circuit 50, a memory 60, and outputinterface circuits 61 and 62. The signal representing the identificationcode and received by the receiving circuit 54 is waveform-shaped in theinput interface circuit 55, and then inputted to the processing circuit50 implemented by a microcomputer, etc. The processing circuit 50determines whether the identification code matches the identificationcode of the vehicle stored in the memory 60 implemented by an EEPROM orthe like, and when they coincide, drives through the output interfacecircuit 61 the actuator 43 implemented by an electromagnetic solenoid orthe like. That is, when the doors and trunk are in locked position, anunlocking operation is performed, and when they are in unlockedposition, a locking operation is performed.

Outputs from the switches 63, 44, and 45, with chattering componentsremoved by the respective input interface circuits 56, 57, and 58, areinputted to the processing circuit 50. With the set switch 63 conductingand thus activating the anti-theft function, when the opening of thehood or door is detected by the hood switch 44 for detecting theopening/closing of the internal-combustion engine hood or by thecourtesy switch 45 for detecting the opening/closing of the door, theprocessing circuit 50 sounds the horn 46 while flashing the stop signalindicator light 47, in the same manner as previously described, thusperforming the theft prevention operation.

When a request to read an identification code is inputted to the inputinterface circuit 59 in the door lock control unit 6 from the outputinterface circuit 22 in the internal-combustion engine control unit 3via a line 71, as will be described later, the processing circuit 50outputs the signal representing the identification code to the inputinterface 15 in the internal-combustion engine control unit 3 throughthe output interface circuit 62 and a line 64.

The control units 3, 5, and 6 are also provided with constant-voltagecircuits 67, 68, and 69, respectively. Power from a battery 66 issupplied to the constant-voltage circuits 67 and 68 when an ignition keyswitch 65 is connected to an IG contact or ST contact, while the powerfrom the battery 66 is constantly supplied to the constant-voltagecircuit 69, to energize the respective circuits in the control units 3,5, and 6.

FIG. 15 is a timing chart for explaining the theft prevention operationof the above-configured vehicle control device 1. When the ignition keyswitch 65 is connected to the IG contact or ST contact at time t1, asshown in FIG. 15(1), the processing circuit 7 initiates aninitialization operation at time t2 when the supply voltage settlesdown, as shown in FIG. 15(2).

As part of the initialization operation, the processing circuit 7 readsthe identification code that was transmitted from the transmitter 41when unlocking the door and stored in the memory 60, via the line 64 inthe manner as shown in FIG. 15 (3). The identification code is thencompared with the identification code prestored in the memory area 20bof the memory 20, to determine whether they coincide. If they do notcoincide, the start inhibit flag F is set to 1, as shown in FIG. 15(4).This inhibits the output, for example, of an injection signal orignition signal, inhibiting the internal-combustion engine fromstarting.

In this way, the receiver 42 which receives the identification codetransmits the received identification code itself, not the result of thecomparison of the identification codes, to the internal-combustionengine control unit 3 via the line 64, and the identification code iscompared in the internal-combustion engine control unit 3 with theidentification code stored in the memory 20 provided to store controldata. Therefore, it is impossible even for persons experienced invehicle electronics to input the identification code through the line 64in a pseudo manner, and thus, the vehicle can be reliably prevented frombeing burgled and driven away.

FIG. 16 is a flowchart for explaining the above-described theftprevention operation. When the ignition key switch 65 conducts and thesupply voltage settles, the process proceeds to step p1, where theprocessing circuit 7 performs the initialization operation. In step p2,a request to read an identification code is sent to the door lockcontrol unit 6 via the line 71. In step p3, the identification code sentfrom the door lock control unit 6 is read in response to the readrequest. In step p4, it is determined whether the identification codethus read matches the identification code stored in the memory 20. Ifthey coincide, the flag F is reset to 0 in step p5, upon which theprocess is terminated. If they do not coincide, the flag F is set to 1in step p6, after which the process returns to step p2 to re-request thereading out of the identification code.

FIG. 17 is a flowchart for explaining the theft prevention operation ofanother embodiment of the invention. The operation shown in FIG. 17 isactivated by interrupt handling at predetermined intervals of timeduring running of the internal-combustion engine 2.

In step q1, it is determined, based on the detection result from thecrank angle detector 12, whether or not the rotational speed Ne of theinternal-combustion engine 2 is equal to or lower than a predeterminedvalue, for example, 800 rpm. If the answer is YES, it is determined instep q2 whether the vehicle speed Vs inputted from the automatictransmission control unit 5 is equal to a predetermined value, forexample, 0 km/h; if the answer is YES in step q2, the process furtherproceeds to step q3, where it is determined, based on the detectionresult from the neutral detector 9, whether the shift lever of theautomatic transmission 4 is in the neutral position, and if YES, theprocess proceeds to step q4.

When the conditions of steps q1 to q3 have been satisfied, that is, whenit is determined that the vehicle is stationary, the process proceeds tostep q4 to send an identification code read request to the door lockcontrol unit 6, as in step p2 described above. In step q5, theidentification code is read, as in step p3, and in step q6, it isdetermined, as in step p4, whether the identification code matches theidentification code stored in the memory 20. If they do not coincide,the flag F is set to 1 in step q7, and the process is terminated. Ifthey coincide, the flag F is reset to 0 in step q8, and the process isterminated.

When any one of the conditions of steps q1 to q3 has not been satisfied,that is, when there is a possibility that the vehicle is running, theprocess jumps to step q8 and the flag F is reset to 0.

Accordingly, even if an erroneous judgment was made in the judgmentprocess shown in FIG. 16, correct judgment can be achieved by performingthe judgment process shown in FIG. 17 after interruption time haselapsed. The fail-safe function can thus be expanded. Furthermore, sincerestarting the internal-combustion engine 2 is allowed when the vehicleis running, if the power supply is temporarily interrupted, for example,by turning the ignition key switch 65 off and on when the vehicle isrunning, the internal-combustion engine 2 can be restarted quicklywithout having to retransmit the identification code from thetransmitter 41.

The processing circuit 7 is also equipped with a test mode terminal 70.The internal-combustion engine control unit 3 can be tested byenergizing the test mode terminal 70. That is, the test mode terminal 70is energized, for example, when performing a delivery inspection at thefactory before shipping or during a fault diagnosis at a repair shop. Inthe present invention, when a predetermined operation is performed intest mode with the test mode terminal 70 energized, the memory 20 is putin a write mode allowing the identification code to be written into thememory area 20b.

More specifically, the write mode is enabled by inputting the OFFcondition of the neutral switch 9 and the ON condition of the startswitch 10 in a pseudo manner to the input interface circuits 18 and 19,respectively.

FIG. 18 is a flowchart for explaining the identification code writeoperation. When the test mode is entered by energizing the test modeterminal 70, the process proceeds to step k1, where it is determinedwhether the neutral switch 9 is off. If the answer is YES, then it isdetermined in step k2 whether the start switch 10 is conducting or not;if the answer is YES in step k2, that is, if a combination of switchinputs that cannot occur during actual driving is thus produced in apseudo manner, the identification code write mode is entered, and theprocess proceeds to step k3.

In step k3, the identification code is read via the input interfacecircuit 15, and in the next step k4, the identification code thus readis written into the memory area 20b of the memory 20, after which theprocess proceeds to step k5. If the condition of step k1 or k2 is notsatisfied, the process Jumps to step k5 to proceeds to the next test.

Accordingly, when there arises a need to rewrite the identification codein the event of a failure of the internal-combustion engine control unit3 or replacement of the transmitter 6 when it is lost or damaged, a newidentification code can be written by performing a predeterminedoperation after activating the test mode; since there is no need toequip the processing circuit 7 with a special terminal for activatingthe write mode, rewriting of the identification code can be accomplishedwith a simple construction. Furthermore, inadvertent rewriting by theuser, etc. can be prevented, which further enhances the effectiveness ofthe theft prevention.

POTENTIAL FOR EXPLOITATION IN INDUSTRY

As described above, according to the invention, when a vehicle theft isdetected, the function of power supply to control means is disabled bycutting off, for example, the base current of a constant-voltage controltransistor in power supply means. Vehicle theft can thus be preventedreliably without the need for large-size components such as a relay usedin a system that involves cutting off the control output of an ignitionsignal, etc.

Preferably, when a theft is detected, the power supply line from thepower supply means to the control means is short-circuited to thegrounding line, and the power supply function to the control means isdisabled by utilizing the overcurrent protection action of the powersupply means. In this way, power supply can be cut off using a simpleconstruction by just providing short-circuiting means.

According to the invention, an initializing means is provided inrelation to the control means, and when a vehicle theft is detected, theinitialization of the control means by the initializing means isinhibited, so that the control means cannot perform calculation ofcontrol amounts even after the supply voltage has risen. Vehicle theftcan thus be prevented reliably.

According to the invention, when a theft is detected, the output of theinjection signal or ignition signal is stopped to the control means thatcontrols at least either the fuel injection quantity or ignition timingof the internal-combustion engine, so that the air-fuel mixture in thecombustion chamber does not ignite. In this way, vehicle theft can beprevented reliably.

Furthermore, according to the invention, in a configuration where backupcontrol means for the control means is provided along with the controlmeans that controls at least either the fuel injection quantity orignition timing of the internal-combustion engine, when a vehicle theftis detected, the control means operates to shorten at least either theinjection signal or the ignition signal to a predetermined infinitesimaltime; since the injection signal or ignition signal from the controlmeans is not completely stopped, the ignition of the air-fuel mixture inthe combustion chamber can be effectively inhibited without activatingthe backup operation, to prevent vehicle theft in a reliable manner.

Preferably, the above signal shortening operation is performed when thevehicle speed has reached or exceeded a predetermined value after thedetection of a vehicle theft. In this way, the anti-theft action can beput into operation only when the vehicle being stolen is started to bedriven away.

According to the invention, since the detector is shut off from thecontrol means upon detection of a theft, the detector output is notinputted to the control means, so that the control means cannot performcalculation of control amounts and the internal-combustion engine cannotbe started. Vehicle theft can thus be prevented reliably.

According to the invention, the shut-off means is inserted in a powersupply line to the detector, and power supply from the power source isstopped upon detection of a theft. By disabling the detector output inthis way, the calculation of the control amounts can be renderedimpossible.

Also preferably, since the result of the detection as to whether thevehicle is being stolen or not is sent to the control means or theshort-circuiting means in the form of a code signal, it is not possibleto reproduce such a code signal by simply setting the line from thedetection means to the control means or the short-circuiting means to ahigh level or low level, attempting to input the result of the detectionin a pseudo manner. In this way, vehicle theft can be prevented furtherreliably.

Furthermore, according to the invention, a storage means is provided inrelation to the control means for controlling the operating conditionsof the internal-combustion engine, and an identification code is storedin the storage means together with the control data; then, an inputtedidentification code is compared in the control means with theidentification code stored in the storage means. That is, the controlmeans itself compares the identification code and verifies its validity,rather than determining whether the starting of the internal-combustionengine should be permitted or not based on the result of the comparisonfrom other comparing means, etc. as in the prior art.

Therefore, it is not possible even for persons experienced in vehicleelectronics to produce an input corresponding to the identification codein a pseudo manner and supply it to the control means. This reliablyprevents vehicle theft.

Preferably, the comparing operation is performed again when therotational speed of the internal-combustion engine is not higher than apredetermined value, for example, 800 rpm, the vehicle speed is at apredetermined value, for example, 0 km/h, and the shift lever of thetransmission is in the neutral or parking position. Therefore, if anerroneous decision was made and the starting of the internal-combustionengine was not permitted during the operation to start theinternal-combustion engine, the internal-combustion engine can bestarted if the identification codes coincide as a result of therejudgement made with the above conditions satisfied. The fail-safefunction can thus be expanded.

Also preferably, when the vehicle speed is higher than a predeterminedvalue, starting of the internal-combustion engine is permittedregardless of the result of the comparison of the identification codes,allowing the internal-combustion engine to be restarted quickly in theevent of an internal-combustion engine stall during driving.

Further preferably, when a combination of parameters that cannot occurduring usual operation of the internal-combustion engine is simulatedand inputted, the input identification code is directly written into thestorage means. Rewriting of the identification code can thus beaccomplished using a simple construction without having to provide aswitch or the like on the control means. Furthermore, since inadvertentrewriting is prevented, vehicle theft can be prevented reliably.

What is claimed is:
 1. An anti-theft device for a vehicle,comprising:control means for controlling at least one of either a fuelinjection quantity or an ignition timing of an internal-combustionengine; and detection means for making the control means stop outputtingof at least either of an injection signal and an ignition signal to theinternal-combustion engine, when a theft of a vehicle is detected. 2.The anti-theft device for a vehicle of claim 1, wherein the detectionmeans transmits a detection result in the form of a code signal.
 3. Ananti-theft device for a vehicle, comprising:control means forcontrolling at least one of either a fuel injection quantity or anignition timing of an internal-combustion engine; and backup controlmeans provided in relation to the control means, for supplying a fixedbackup injection signal or a fixed backup ignition signal to theinternal-combustion engine when it is detected that an injection signalor an ignition signal to the internal-combustion engine has stopped; anddetection means for detecting a theft of a vehicle; wherein, when atheft is detected by the detection means, the control means shortens atleast either the injection signal or the ignition signal to apredetermined infinitesimal time.
 4. The anti-theft device for a vehicleof claim 3, wherein the detection means transmits a detection result inthe form of a code signal.
 5. The anti-theft device for a vehicle ofclaim 3, wherein the control means performs the shortening of theinjection signal or the ignition signal when vehicle speed reaches orexceeds a predetermined value after detection of the theft of thevehicle.
 6. An anti-theft device for a vehicle, comprising:control meansfor controlling operating conditions of an internal-combustion engine:power supply means, having a semiconductor switch, for stabilizing powerfrom a battery and supplying the power via said semiconductor switch tosaid control means; and detection means for controlling saidsemiconductor switch to stop said power supply means from supplyingpower to said control means when a theft of the vehicle is detected. 7.The anti-theft device for a vehicle of claim 6, wherein the detectionmeans transmits a detection result in the form of a code signal.
 8. Ananti-theft device for a vehicle, comprising:control means forcontrolling operating conditions of an internal-combustion engine; powersupply means for stabilizing power from a battery and supplying thepower to the control means; a power source line connected from the powersupply means to the control means; short circuit means disposed betweenthe power source line and a grounding line for short circuiting thepower supply to the control means; and detection means for stopping thepower supply means from supplying power to the control means, upondetection of a theft of the vehicle; wherein, the power supply means isfor automatically shutting off the power supply to the control meansupon overcurrent detection, and the detection means is for activatingthe short circuit means to cause generation of an overcurrent, upondetection of a theft of the vehicle.
 9. The anti-theft device for avehicle of claim 8, wherein the detection means transmits a detectionresult in the form of a code signal.
 10. An anti-theft device for avehicle, comprising:control means for controlling operation conditionsof an internal-combustion engine; initializing means, for supplying aninitialization signal to an initial terminal of said control means atthe time when a supply voltage rises and thereby making calculation ofcontrol amounts possible; and detection means for inhibiting the supplyof the initialization signal from said initialization means in order toinhibit said control means when a theft of the vehicle is detected. 11.The anti-theft device for a vehicle of claim 10, wherein the detectionmeans transmits a detection result in the form of a code signal.
 12. Ananti-theft device for a vehicle, comprising:a detector for detectingcontrol parameters of an internal-combustion engine and for outputting acontrol detection result; control means for calculating a control amountbased on the control detection result from the detector, and forsupplying a control output to the internal-combustion engine; detectionmeans for detecting a theft of the vehicle; and shut-off meansinterposed between the detector and the control means, for shutting offan output from the detector in order to inhibit the control means when atheft is detected by the detection means.
 13. The anti-theft device fora vehicle of claim 12, wherein the detection means transmits a detectionresult in the form of a code signal.
 14. An anti-theft device for avehicle, comprising:a detector for detecting control parameter of aninternal-combustion engine and for outputting a control detectionresult; control means for calculating a control amount based on thecontrol detection result from the detector, and for supplying a controloutput to the internal-combustion engine; detection means for detectinga theft of the vehicle; and shut-off means interposed in a power supplyline to the detector, for shutting off the power supply line to disablethe detector to inhibit the output of the detection result to thecontrol means when a theft is detected by the detection means.
 15. Theanti-theft device for a vehicle of claim 14, wherein the detection meansis for transmitting a detection result in the form of a code signal. 16.An anti-theft device for a vehicle, comprising:control means forcontrolling at least one of either a fuel injection quantity or anignition timing of an internal-combustion engine; storage means having astorage area for storing data relating to control of theinternal-combustion engine and a storage area for storing anidentification code; and input means for inputting an identificationcode to the control means by a predetermined operation; wherein, whenthe control means is energized with an attempt to start theinternal-combustion engine, the control means compares theidentification code inputted from the input means with theidentification code stored in the storage means, and when theidentification codes do not coincide, the control means inhibits outputof at least either one of an injection signal and an ignition signaloutputted to the internal-combustion engine.
 17. The anti-theft devicefor a vehicle of claim 16, wherein the control means is for comparingthe identification codes again when rotational speed of theinternal-combustion engine is not higher than a predetermined value,vehicle speed is not higher than a predetermined value, and atransmission shift lever is in a parking or neutral position.
 18. Theanti-theft device for a vehicle of claim 17, wherein, when vehicle speedis not lower than a predetermined value, output of at least either oneof the injection signal and the ignition signal the internal-combustionengine is permitted regardless of the result of the comparison betweenthe identification codes.
 19. The anti-theft device for a vehicle ofclaim 17, wherein, when parameters to be used to control theinternal-combustion engine are inputted in a combination that cannotoccur during a usual operation of the internal-combustion engine, thecontrol means writes the identification code inputted from the inputmeans, into the storage means.
 20. The anti-theft device for a vehicleof claim 16, wherein, when parameters to be used to control theinternal-combustion engine are inputted in a combination that cannotoccur during a usual operation of the internal-combustion engine, thecontrol means writes the identification code inputted from the inputmeans, into the storage means.
 21. The anti-theft device for a vehicleof claim 16, wherein, when vehicle speed is not lower than apredetermined value, output of at least either one of the injectionsignal and the ignition signal to the internal-combustion engine ispermitted regardless of the result of the comparison between theidentification codes.